Citation: Boiocchi, M.; Callegari, A.; Ottolini, L. (2006). The crystal structure of piergorite-(Ce), Ca8Ce2(Al0.5Fe3+0.5)Sum1(X,Li,Be)2Si6B8O36(OH,F)2: A new borosilicate from Vetralla, Italy, with a modified hellandite-type chain. American Mineralogist, 91, pp. 1170-1177.